Cushioning materials have a variety of uses, such as for mattresses, seating surfaces, shoe inserts, packaging, medical devices, etc. Cushioning materials may be formulated and/or configured to reduce peak pressure on a cushioned body, which may increase comfort for humans or animals, and may protect objects from damage. Cushioning materials may be formed of materials that deflect or deform under load, such as polyethylene or polyurethane foams (e.g., convoluted foam), vinyl, rubber, springs, natural or synthetic fibers, fluid-filled flexible containers, etc. Different cushioning materials may have different responses to a given pressure, and some materials may be well suited to different applications. Cushioning materials may be used in combination with one another to achieve selected properties.
For example, cushioning materials may include a foam layer topped with a layer of thermoset elastomeric gel, such as a polyurethane gel or a silicone gel. Because polyurethane gels and silicone gels are generally structurally weak and/or sticky, cushioning materials may include film covering such gels, such as a thin thermoplastic polyurethane film. The film may reinforce the strength of the gel, and may prevent other materials from sticking to the gel, since the film generally adheres to the gel but is not itself sticky.
Gels may be used for cushioning and/or temperature management. Gels may provide cushioning because the gels may hydrostatically flow to the shape of a cushioned object and may tend to relieve pressure peaks and/or reduce stresses from shear. Gels may have high thermal mass and/or thermal conductivity, and may therefore be used for heating (such as in hot packs for sore muscles), cooling (such as in cold packs for sprains or for a feeling of coolness when lying on a mattress), or maintaining a given temperature (such as in a mattress being used in a too-warm or too-cool room). For example, gel may be fused to the top of a mattress core, and a film may cover the gel. As another example, gels may be used as the top layer of a foam wheelchair cushion.
A conventional gel layer, with or without a plastic film, may be a barrier to gases (e.g., air, vapors, or other gases). This barrier may cause difficulties such as discomfort, such as when body heat and/or perspiration accumulate between the user's body and the gel layer. Even when a breathable material (such as a foam cover or batting fiber) is disposed between a cushioned object and the gel, gases can only travel laterally through the breathable material. Since gases cannot penetrate the plastic film or the gel, the plastic film or the gel inhibits the flow of the gases away from the cushioned object. When the weight of the cushioned object compresses the breathable material, the lateral gas flow paths may become more constricted. Thus, it would be beneficial to provide a cushioning material that alleviates some of these concerns.